Re: [xj-s] Strange wire in trunk

[Walter Petermann <corsaro@brokersys.com>]

Jim Isbell wrote:
> 
> I was poking around in the trunk yesterday when the alternator failed and
> founf a wire tucked behind the battery.  It has two connectors on it both
> are red.  One of the connectors had a jumper to jumper the two wires
> together.  The other is a four pin in line connector with a cap over the end.
> 
> What the duce is this?  

Jim,
the 2 wire jumper disables O2 feedback in park and neutral. It's in 
series with the park/neutral signal from the gear shift lever to the 
ecu. When you take the car for an emissions test, you need to remove
this jumper so that the computer can run in closed loop in park (Isn't
this cheating? :).
The four wire connector is used to monitor what the ecu is doing
while in closed loop. This way you can check if the engine is running
too rich or too lean or maybe one side richer than the other.
The green/pink wire is the driver's side bank, the green/white is for
the passenger side. Black is ground.
In closed loop the voltages should vary up/down between about 2.5 to 3 
volts. A lower voltage means that the ecu is trying to lean the mixture
in that bank, or, the mixture is too rich. A high voltage means that the
bank is lean.
In practice I would just make sure that the voltage is not constantly
below 2.2 or constantly above 3.5 ..excuse me a second..watching Brazil
Holland penalty kicks.....

Holland is out! Anyway, I would check that the difference between left
and right bank is not more than ~0.5v . You can set the idle mixture
with the idle mixture pot on the side of the ecu. Factory setting is
6 'clicks' back from full rich +/-1 . Then check at 2500rpm.

The green/white wire is the power to the ecu.

that's the duce
 regards,
 Walter

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Follow-Ups:

• Re: [xj-s] Strange wire in trunk
• From: sean.straw+Jaguar@mail.professional.org (Sean Straw)

References:

• [xj-s] Strange wire in trunk
• From: Jim Isbell <jisbelljr@mail.utexas.edu>

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